A Mechanosensory Circuit that Mixes Opponent Channels to Produce Selectivity for Complex Stimulus Features.

Johnston’s organ is the largest mechanosensory organ in Drosophila; it analyzes movements of the antenna due to sound, wind, gravity, and touch. Different Johnston’s organ neurons (JONs) encode distinct stimulus features. Certain JONs respond in a sustained manner to steady displacements, and these JONs subdivide into opponent populations that prefer push or pull displacements. Here, we describe neurons in the brain (aPN3 neurons) that combine excitation and inhibition from push/pull JONs in different ratios. Consequently, different aPN3 neurons are sensitive to movement in different parts of the antenna’s range, at different frequencies, or at different amplitude modulation rates. We use a model to show how the tuning of aPN3 neurons can arise from rectification and temporal filtering in JONs, followed by mixing of JON signals in different proportions. These results illustrate how several canonical neural circuit components – rectification, opponency, and filtering – can combine to produce selectivity for complex stimulus features.

约翰斯顿氏器官是果蝇中最大的机械感觉器官；它分析由声音、风、重力和触觉引起的触角运动。不同的约翰斯顿氏器官神经元（JONs）对不同的刺激特征进行编码。某些JONs对稳定位移以持续的方式作出反应，并且这些JONs可细分为偏好推或拉位移的对立群体。在此，我们描述了大脑中的神经元（aPN3神经元），它们以不同的比例组合来自推/拉JONs的兴奋和抑制。因此，不同的aPN3神经元对触角活动范围内不同部分的运动、不同频率或不同的调幅速率敏感。我们使用一个模型来展示aPN3神经元的调谐如何源于JONs中的整流和时间滤波，以及随后不同比例的JON信号的混合。这些结果阐明了几种典型的神经回路成分——整流、对立和滤波——如何结合以对复杂的刺激特征产生选择性。